1. Field of the Disclosure
The present disclosure relates to a Ti-precursor, a method of preparing the same, a method of preparing a Ti-containing thin layer by using the Ti-precursor and the Ti-containing thin layer, and more particularly, to a Ti-precursor which can be deposited at low temperatures, a method of preparing the same, a method of preparing a Ti-containing thin layer by using the Ti-precursor and the Ti-containing thin layer.
2. Description of the Related Art
A semiconductor technology has been progressed continuously by pursuing more improved technology through miniaturizing semiconductor devices, and research on a process using a thin layer material suitable for such miniaturization is actively progressing.
Particularly, a Ti-containing thin layer is being employed in several fields for semiconductor devices.
For example, a TiO2 thin layer for high density-dynamic random access memory (DRAM) is a thin layer having the highest dielectric constant of monolayers, and can be employed as various insulating layers. A TiN thin layer can be employed as a lower electrode in the high density-DRAM. Further, a TiN thin layer can be employed as an interconnection metal, for example, an adhesion layer for depositing Cu, etc.
Further, the Ti-containing thin layer includes a barium strontium titanate (BST) thin layer which can be used in a capacitor for DRAM, a lead zirconate titanate (PZT) thin layer which can be used in a ferroelectric random access memory (FRAM), a strontium bismuth titanate (SBT) thin layer, a bismuth lanthanum titanate (BLT) thin layer, etc.
There are diverse methods of preparing such Ti-containing thin layers. Of those methods, chemical vapor deposition (CVD) employing a Ti precursor is a process in which after the Ti precursor is vaporized, the desired thin layer made of solid material is synthesized through chemical reaction. The process can control forming a final thin layer at the molecular level. Further, a thin layer that has excellent large-area uniformity, can be applied over a large area, and an excellent step coverage on the surface of a substrate without damage, can be obtained.
A Ti precursor used in the CVD is described in, for example, Korean Patent Laying-Open No. 2002-0016748. The Ti precursor of the patent application consists of a tridentate ligand having valence of −2, and Ti.
Such a Ti precursor should satisfy various requirements such as high vapor pressure, high purity, low deposition temperature, high deposition rate, ease to handle, non-toxicity, and low cost, etc.
FIG. 1 shows conventional Ti precursors and their respective deposition temperatures. Referring to FIG. 1, in order to form a Ti-containing thin layer, the precursor A requires deposition temperatures of more than about 360° C., the precursor B requires deposition temperatures of more than about 300° C., the precursor C requires deposition temperatures of more than about 375° C., the precursor D requires deposition temperatures of more than about 330° C.
As described above, when conventional precursors are employed, a range of high deposition temperatures is required in order to form a Ti-containing thin layer having an electrical property suitable for application in various devices. However, this may result in damage in devices by the high temperature, and an increase in production costs and process time. Accordingly, a novel Ti precursor that can be deposited at low temperatures is needed.